Blue Whale Study’s primary research focus in recent years has been aerial surveys which show the distribution of blue whales across a wide area over multiple seasons. We have investigated and modelled blue whale habitat over a very large area between Bass Strait and the Great Australian Bight, by correlating aerial survey sightings data with habitat variables such as depth, and satellite-derived sea surface temperature and surface chlorophyll (i.e. phytoplankton).This research has helped us to understand and describe areas of importance to blue whales, movement patterns of whales during upwelling seasons, and how varying upwelling intensity across seasons influences blue whale abundance.
We have also conducted ecological research to examine blue whale habitat at a finer scale, using our small vessel Bonney Blue to conduct surveys in a focal area near the centre of the feeding ground (near Portland Victoria). Our boat based studies have investigated the whales’ prey (krill) and foraging behaviour, using a specialised depth sounder to record the underwater presence of krill and fish, and suction-cup-attached dive loggers to record the underwater trajectory of the whales as they searched for krill. At the same time we searched visually for blue whales and took oceanographic measurements to examine the upwelling structure and behaviour of the ocean.In 2005 we tagged several blue whales with satellite tags, hoping to track their large-scale migratory movements to tropical wintering grounds. Unfortunately these tags did not remain attached to the whales for long enough to provide this information, but they gave us some valuable short-term data on how blue whales foraged within the Bonney Upwelling, and perhaps more importantly, they showed us that blue whales can rapidly move from the Bonney Upwelling south to the Subtropical Convergence, a major oceanic region and likely blue whale feeding area where Soviet whalers secretly and illegally killed many blue whales during the 1960s. Satellite tagging is now used by many research groups and has provided a wealth of interesting data about whale movements, but Blue Whale Study has ethical concerns about the deeper-implanting tags now in use, that give longer attachments, and if we resume tagging we will do using tag designs, such as the LIMPET tag, that do not implant so deeply into the whales.
At sea we routinely conduct photo-identification (photo-ID) which will likely be a major focus of BWS research again in coming years. Photo-ID involves photographing the distinctive pigmentation patterns on blue whales’ flanks, for comparison with images in databases held by ourselves and blue whale researchers elsewhere. It enables us to develop life history data for individual whales, including movements, calving intervals, associations between individuals, individual residence periods in certain areas, and so on. In recent years we have also realised that it allows us to monitor the health of blue whales from their appearance, as we have noted evidence of ‘skinny’ whales (emaciation), parasite infestations and skin disease. We can also monitor the welfare of whales that have been tagged by other research groups, a necessary follow-up to tagging.
For several years we were involved in biopsy sampling, the collection of a small amount of skin from free-swimming whales, for genetic analysis. It has enabled us to learn the sex of each individual (to go with individual photo-ID), as well as the population group to which the whale belongs (‘Indian Ocean’ pygmy blues). In this way we have contributed to and understanding of the ‘population structure’ of blue whales and their various subspecies in the Southern Hemisphere, which has important conservation implications.
For years we have monitored upwelling dynamics by deploying temperature loggers, which record temperature at varying depths, for months at a time. Further deployments are planned during the 2016-17 summer. We have also deployed passive acoustic loggers to record blue whale calls over periods of months. This helped to put local blue whale calls into a global context, to indicate impacts from human activities, and allow tracking of blue whale movements.
The multidisciplinary research that we are engaged in requires a range of skills and backgrounds. We have therefore collaborated with a diversity of research groups from Australia and overseas, which has been an exciting and rewarding part of our work. For many years the blue whale research community in Australia was small and closely knit, but this small group of researchers has added to our understanding of blue whales well beyond what could have been imagined 20 years ago.